Heterogeneous catalysis in supercritical water

Fluids at temperatures and pressures near their thermodynamic critical points are attracting attention as media for heterogeneous catalytic reactions. Several factors have motivated this interest in catalytic reactions in supercritical fluids (SCFs), but the paradigm of pollution prevention is one of the most important. The increased awareness of environmental sustainability and the trend toward pollution prevention has led to a consideration of environmentally benign solvents such as supercritical water for chemical processes. This article provides an overview of the types of heterogeneous catalytic reactions that have been accomplished in supercritical water. Additionally, we provide new experimental results for the heterogeneous catalytic oxidation of phenol in supercritical water over bulk TiO₂ and compare the performance of different transition metal oxide catalysts for this reaction.